It is recognized that many electronic devices and/or parts therefor, generically referred to herein as electronic components, are extremely sensitive to jarring or vibration during shipping of the components to end users or in simply transporting the components from one department to another during the manufacturing process. Due to this sensitivity to jarring and vibration, foams including polyurethane foams have been suggested and utilized as packaging materials as well as a jar or vibrational dampener in transporting electronic components from one position or location to another during their manufacture. It was soon determined, however, that such foams including polyurethane foams by being in contact with electronic components through sliding, rubbing or separation of materials, or simply being in contact with plant personnel or in a plant environment will build up a static electrical charge sufficient to cause arcing and consequent damage to electronic components. To alleviate the problem caused by this build-up of static electricity, efforts have been made to produce foams which have antistatic properties as exemplified by U.S. Pat. No. 4,231,901. U.S. Pat. No. 4,231,901 discloses electrically conductive foams adapted for use with electronic components sensitive to static charges. These foams have a conductive material such as carbon black impregnated into the foam and bonded thereto with a film-forming polymeric material. Suitable film-forming polymeric materials include elastomeric polymers such as the butadiene-styrene resins as well as the acrylic polymers and the like. As is apparent, the process of producing the antistatic foams is a multi-step process requiring the uniform dispersion or impregnation of the foam with first the conductive material and then bonding with the polymeric binding agent. U.S. Pat. No. 3,933,697 also discloses an antistatic polyurethane foam. According to U.S. Pat. No. 3,933,697, select quaternary ammonium salts are incorporated into a polyurethane foam either by impregnation of a pre-made foam or by including the quaternary ammonium compound in the foam-forming composition when the foam is produced. As seen from the '697 patent, the amount of quaternary ammonium compound which can be incorporated into the foam without detriment to the desired foam properties must be carefully controlled.
Although the aforesaid prior art provides antistatic foams which are useful, antistatic polyester polyurethane foams are still essential which have good foam properties including uniform cell size, freedom from pinholing, good structural stability and strength, and superior flame lamination characteristics, including the ability to retain the antistatic agents during use while still being economical to produce.